I have a 2000 XK8. Have owned it almost two years. The previous owner didn't like the standard wheels on the XK8. So he had a set of four XKR wheels installed with new tires. Looks great. Except for one thing. The XKR wheels are one inch bigger in diameter. On a trip I calibrated the odometer add found it read about five percent low. No problem so far. But!!! The spare is the original spare which is one inch smaller than the other four. If I ever have to use the spare what problems am I going to have with one wheel spinning at a different rpm than the other three? I would think the ABS system just might not like that.

Your thoughts are greatly appreciated.

EZDriver

Alternative wheels are a regular and popular upgrade with owners often going for bigger rims to improve appearance. Original 17 inch replaced with 18 inch or more. The bigger the rim, the skinnier the tyre size used so you see more alloy and less rubber.

Are you comparing the overall diameter of the wheel assembly - the rim with fitted tyre - or comparing rim diameters alone?

Graham

As long as you don't plan on running the spare permanently you'll have no issues. Some ABS systems can adapt to small differences, others may set a code. Most, but not all, ABS systems shut down when a code is set. However, your car should then stop shorter in panic/hard braking situations. ABS only helps you avoid skidding and gives you some slight ability to steer while braking on slick/loose surfaces.

Handy little program I use a lot. --> Tire size calculator
Take a look at this and put in your differing tire & wheel sizes.
I'm running tires that are the next size taller than stock. Still have the original Pirelli spare that's never been on the ground.

Mike
(now let's see what Murphy says about that.. .)